#include <iostream>
#include <vector>
#define NDEBUG
using std::vector; using std::cout; using std::endl;
void printVec(vector<int> &vec){
#ifndef NDEBUG
    cout << "vector size: " << vec.size() << endl;
#endif
    if (!vec.empty()){
        auto tmp = vec.back();
        vec.pop_back();//
        printVec(vec); cout << tmp << " ";
    }}
int main(){
    vector<int> vec{ 1, 2, 3, 4, 5, 6, 7, 8, 9 };
    printVec(vec);    cout << endl;
return 0; }
